Batting, boards and other composite products for thermal and acoustical insulation typically include one or more layers of a low density web of nonwoven fiber or foamed insulating material. Frequently, improved properties and enhanced performance are sought by coating a face of the composite with a cover layer. For example, to increase stiffness, provide puncture protection, or reduce permeability, paper, foil, and/or film is sometimes laminated to the face.
Occasionally a very flexible, continuous skin on the insulating material is desired. A cover layer of this type can be produced from a liquid capable of curing by drying or reacting. However, it can be very difficult to efficiently coat insulation material with a liquid because the fibrous or foamed substrate is very porous and has a roughly textured surface. Hence, the cover layer normally needs to be very thick to fill the pores so as to provide continuous coverage. As a result, conventional covered insulation materials consume an excessive amount of coating material.
Frequently low density webs of non woven or foamed insulation material are flexible and resilient. This characteristic adds to the difficulty of casting a liquid onto the very open surface. Traditional coating machines for resilient webs typically involve picking up coating liquid onto a smooth surface of a drum rotating in a trough of the liquid and transferring the liquid onto the underside of moving web. Then excess liquid is scraped from the underside by a bar FIG. 1 of U.S. Pat. No. 4,456,637 exemplifies an apparatus for this process. This type of apparatus functions best for low viscosity coating liquids. Because the coating liquid for low density, resilient, porous insulating webs is usually highly viscous, an underside coating technique normally is unacceptable.
Roughly textured surfaces can be coated with a viscous liquid by laying a bead of casting liquid on top of the horizontal substrate then dragging a straight profile doctor blade across the surface. Because the doctor blade rides on the highest points of the textured surface, the coating is deep over the surface pores and shallow where the substrate fiber or foam structure ascends to peaks. The peaks of the substrate sometimes protrude above the cover layer. The thickness of a cover layer on a roughly textured composite made with a straight doctor blade thus tends to vary to an unacceptable extent.
It is desirable to have a roughly textured composite, such as insulation batting or board, with a uniform thickness, flexible cover layer cast from a curable liquid Accordingly, there is now provided a composite comprising at least one body layer having a roughly textured face and a cover layer of a solid of a cured liquid cast on the textured face, in which the cover layer has a substantially uniform thickness and is permanently embedded into the body layer to a depth less than the thickness.
A novel apparatus for applying a uniform thickness cover layer onto a roughly textured composite also has been discovered, This apparatus for casting a uniform thickness of a curable liquid onto an upper surface of a horizontally moving web comprises                a pair of parallel, laterally spaced apart vertical side plates, each plate defining a bottom edge;        a coating bar disposed horizontally between the side plates above the bottom edges, the coating bar having a corrugated axial profile defined by a plurality of alternating downwardly facing ridges and grooves;        support means for carrying the moving web in contact with the downwardly facing ridges in a machine direction parallel to the plates; and        nozzle means upstream of coating bar and between the plates for delivering the curable liquid onto the upper surface of the moving web.        
There is further provided a process for making an insulation composite comprising the steps of                placing in a substantially horizontal position a body layer of insulating material having an upwardly directed, roughly textured face;        casting a liquid capable of curing to a solid onto the textured face;        moving the body layer horizontally relative to a horizontally disposed coating bar having a downwardly facing corrugated axial profile defining alternating ridges and grooves such that the ridges contact the face;        pressing a first portion of the liquid in proximity of the ridges into the body layer while passing a second portion of the liquid through the grooves;        allowing the second portion of the liquid to settle in a substantially uniform thickness layer over the first portion of liquid; and        curing the liquid to a solids thereby producing a cover layer of substantially uniform thickness permanently embedded in the face of the body layer.        
Yet further this invention provides an insulation composite produced according to the aforementioned novel process.